title: Cholera outbreak in South Africa, 2008-2009: laboratory analysis of Vibrio cholerae O1 strains.
abstract: BACKGROUND
  A total of 720 Vibrio cholerae O1 strains were recovered for investigation from an outbreak of cholera in South Africa between November 2008 and April 2009.
  
  
  METHODS
  Strains were characterized by serotype testing. Antimicrobial susceptibility testing. Genetic diversity of 248 strains was investigated using pulsed-field gel electrophoresis (PFGE) analysis. Extended characterization was performed on 90 strains. Molecular analysis included: polymerase chain reaction (PCR) identification of ctxA and tcpA genes, sequencing the ctxAB gene, and investigation of molecular mechanisms conferring antimicrobial resistance.
  
  
  RESULTS
  The majority of strains were characterized as serotype Ogawa. Strains showed multidrug resistance. Approximately 1.0% of strains displayed extended-spectrum β-lactamase (ESBL) activity. Strains showed very similar PFGE patterns. Ninety strains selected for extended characterization showed the following results: Strains possessed the cholera toxin (CT) and all were PCR positive for the tcpA-El Tor variant. Sequencing of the ctxB gene matched the B-1 allele. Strains harbored the SXT element. Strains that displayed ESBL activity possessed a 140-kilobase-pair plasmid that produced the TEM-63 β-lactamase. Nalidixic acid-resistant strains harbored mutations in GyrA (Ser83-Ile) and ParC (Ser85-Leu).
  
  
  CONCLUSIONS
  These data highlight the rapid development of antimicrobial resistance and spread of V. cholerae O1 El Tor variants expressing the classical CT within South Africa.
authors.affiliation: Centre for Enteric Diseases, National Institute for Communicable Diseases, Division in the National Health Laboratory Service, Johannesburg.
authors.forename: Husna
authors.initials: H
authors.lastname: Ismail
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Smith
authors.forename: Nomsa P
authors.initials: NP
authors.lastname: Tau
authors.forename: Arvinda
authors.initials: A
authors.lastname: Sooka
authors.forename: Karen H
authors.initials: KH
authors.lastname: Keddy
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002771:Cholera / Q000453:epidemiology* / Q000382:microbiology*; D027081:DNA Gyrase / Q000235:genetics / Q000378:metabolism; D027101:DNA Topoisomerase IV / Q000235:genetics / Q000378:metabolism; D004196:Disease Outbreaks; D024901:Drug Resistance, Multiple, Bacterial; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D009154:Mutation; D012703:Serotyping; D013019:South Africa / Q000453:epidemiology; D041241:Vibrio cholerae O1 / Q000145:classification* / Q000187:drug effects; D014774:Virulence
chemical_list: D000900:Anti-Bacterial Agents; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase
keywords: SXT element; South Africa; TEM-63 β-lactamase; Vibrio cholerae O1 El Tor variant; cholera outbreak; classical cholera toxin; multidrug-resistant